The complexity of the musculo-skeletal system is often a great problem for the medical student. To effectively learn muscles, one needs a clear and logical grouping in systems with definite structures. Besides supplying a thorough description of origin, insertion, function and innervation, this article will provide medical students with a tabular overview that will help to better visualize the muscle groups. Attention: Due to contradictory statements in primary literature, it is highly recommended to always use the most current versions for learning.

Our musculoskeletal system is a complex machinery of bones, joints, muscles, and their auxiliaries, which serve as the body's supporting structure and give the body the ability to move. Our skeletal muscles provide the moving strength and may be low or high in their muscle tone. They have different courses from origin to insertion and also differ in their function. In the following article, you will receive a concise overview of 10 important muscles of our musculoskeletal system.

00:00
Now, we will shift our attention to a region
of the posterior cervical area between theupper two cervical vertebrae and the occiput
or the occipital bone of the skull. This regionis referred to as the suboccipital region.
We will highlight the four pairs of suboccipitalmuscles that reside here, we will define a
geometric configuration, yet another triangleand we will identify a very important blood
vessel that runs within this suboccipitaltriangle.
00:40
But, the muscles that are of interest here
in the suboccipital region will be our rectuscapitis major or simply the rectus major,
that’s this muscle here. This muscle that’sshorter and lie medial to it, is your rectus
capitis posterior minor or simply rectus minor.
01:04
We also have two muscles that are obliquely
oriented. Here is your obliquus capitis inferioror simply the inferior oblique. This muscle that
really is oriented more vertically than obliquelyis your obliquus capitis superior or simply
the superior oblique and your suboccipitaltriangle will be defined by the superior oblique,
the rectus major and then your inferior obliqueand here is your triangle, right in through
here. The vertebral component that you seelying deeper within the triangle is a portion
of the posterior arch of the first cervicalvertebra and then running on the superior
aspect of that arch we have our vertebralartery.
02:09
Now, we will wanna understand the attachments,
innervation and the actions of the individualsuboccipital muscles. We will begin with the
rectus capitis posterior major or simply rectusmajor. So again, the muscle shown here in
the illustration, it’s going to take itspoint of origin from the spinous process of
C2, this will be a very important landmarkin this area. The point of insertion is onto
the occipital bone and it’s going tobe just on the lateral portion of the occipital
bone below a line that’s called the inferiornuchal line. So, that will be this area of
attachment or insertion right along here.
02:58
These suboccipital muscle, as well as the
other three, are innervated by branches ofthe same nerve. This would be the dorsal or
posterior ramus of the first cervical nerve,it does have the name suboccipital. The action
of the rectus major is to extend the headand it can rotate the head to the same side,
so if the right rectus major contracting,it will rotate your head to the right or the
same side.
03:41
The rectus capitis posterior minor or simply
rectus minor will have a more superior pointof origin. It is originating from the posterior
tubercle of the first cervical vertebra, itthen has an insertion onto the occiput, just
medial to the major and just below the inferiornuchal line.
04:10
Innervation, we have already described, suboccipital
nerve. Action of this muscle would be principallyto extend the head, it’s too medial to really
provide any rotation.
04:26
We also have the inferior oblique. Its point
of origin is from the spinous process of C2.
04:37
It crosses superiorly and laterally and if
we look at our bony landmark here laterally,that is the transverse process of the first
cervical vertebra. Innervation, again, issuboccipital nerve and the action of this
muscle is to rotate the skull to the sameside, so if the right inferior oblique is
contracting, shortening, you will rotate yourskull to the right.
05:08
The last muscle of this region is your superior
oblique. It is taking origin from the transverseprocess of C1 as we can nicely see here, it
ascends and attaches to the occipital boneof the skull and it’s going to have a more
superior attachment to the occipital bone,it’s going to be above the inferior nuchal
line, but below the superior nuchal line.
05:34
Innervation, suboccipital nerve and it will
help extend the head and will also help tobend it to the same side, if it’s working
unilaterally. So, if the right one, as shownhere, shortens, your skull will bend to the
right.

About the Lecture

The lecture Suboccipital Muscles – Back Muscles by Craig Canby, PhD is from the course Abdominal Wall.

Included Quiz Questions

What is the nerve supply of rectus capitis posterior major or rectus major?

Suboccipital nerve.

Long thoracic nerve.

Thoracoabdominal nerves.

Obturator nerve.

Supratrochlear nerve.

Which one of the following is a suboccipital nerve?

Posterior ramus of first cervical nerve.

Anterior ramus of first cervical nerve.

Posterior ramus of second cervical nerve.

Anterior ramus of second cervical nerve.

Anterior ramus of third cervical nerve.

What is the origin of Inferior oblique muscle of the Suboccipital muscle group?

Spinous process of C-2.

Spinous process of C-1.

Spinous process of C-3.

Spinous process of C-4.

Spinous process of C-5.

Author of lecture Suboccipital Muscles – Back Muscles

Craig Canby, PhD

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